PAYMENT IS IMPOSSIBLE

I wanted to orderhttps://www.decathlon.fr/mh-100-cat3-id_8329069.html
When I click on "Validate Basket", the window turns gray.
I ADD OTHER ARTICLES ........
FINAL PAYMENT IS IMPOSSIBLE.
I tried 3 times without success.
I called the site "Decathlon" which invited me to use Chrome. I managed to place my order on Chrome.

(DNAWIZ-43385)

How to know if the problem comes from the site or if it comes from Opera?